title: Occupational exposure to low doses of ionizing radiation and cataract development: a systematic literature review and perspectives on future studies.
abstract: Ionizing radiation is a well-known but little understood risk factor for lens opacities. Until recently, cataract development was considered to be a deterministic effect occurring at lens doses exceeding a threshold of 5-8 Gy. Substantial uncertainty about the level and the existence of a threshold subsists. The International Commission on Radiation Protection recently revised it to 0.5 Gy. Based on a systematic literature review of epidemiological studies on exposure to low levels of ionizing radiation and the occurrence of lens opacities, a list of criteria for new epidemiological studies was compiled, and a list of potential study populations was reviewed. Among 24 publications finally identified, six report analyses of acute exposures in atomic bomb survivors and Chernobyl liquidators, and the others report analyses of protracted exposures in occupationally, medically or accidentally exposed populations. Three studies investigated a dose threshold: in atomic bomb survivors, the best estimates were 1 Sv (95 % CI <0-0.8 Sv) regarding lensectomies; in survivors exposed as children, 0.6 Sv (90 % CI <0.0-1.2 Sv) for cortical cataract prevalence and 0.7 Sv (90 % CI 0.0-2.8 Sv) for posterior subcapsular cataract; and in Chernobyl liquidators, 0.34 Sv (95 % CI 0.19-0.68 Sv) for stage 1 cataract. Current studies are heterogeneous and inconclusive regarding the dose-response relationship. Protracted exposures and high lens doses occur in several occupational groups, for instance, in physicians performing fluoroscopy-guided interventional procedures, and in accidentally exposed populations. New studies with a good retrospective exposure assessment are feasible and should be initiated.
authors.affiliation: Institute for Medical Biostatistics, Epidemiology and Informatics-IMBEI, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany. gael.hammer@unimedizin-mainz.de
authors.forename: Gaël P
authors.initials: GP
authors.lastname: Hammer
authors.forename: Ulrike
authors.initials: U
authors.lastname: Scheidemann-Wesp
authors.forename: Florence
authors.initials: F
authors.lastname: Samkange-Zeeb
authors.forename: Henryk
authors.initials: H
authors.lastname: Wicke
authors.forename: Kazuo
authors.initials: K
authors.lastname: Neriishi
authors.forename: Maria
authors.initials: M
authors.lastname: Blettner
mesh_terms: D002386:Cataract / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D016273:Occupational Exposure / Q000009:adverse effects*; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000453:epidemiology* / Q000209:etiology; D011839:Radiation, Ionizing